The pulverized coal mixer is one of the important equipments in the middle storage type boiler. Its normal operation is the key to ensure the stable combustion of the pulverized coal boiler. Combing with the positive pressure off powder occurred in pulverized coal mixer of a 300 MW unit boiler under full load conditions

this paper carried out numerical simulation to analyse the flow field and particle trajectories by using the Fluent software. The large on-way resistance and local resistance of the primary air pipe behind the coal mixer and the defects in structural design of the pulverized coal mixer are considered as the major reasons for off powder. To solve this problem

it suggests that the coal mixer tray should be moved vertically down by 60 mm

and the inner side of the powder inlet be longitudinally extended by 30 mm. Moreover

numerical simulation and experiments were performed to verify the optimized structure. The results show that

after structure optimization

under full load condition

the pulverized coal output of coal mixer for a single primary air pipe increased by 3 t/h

and the coal flow at the outlet was uniform and smooth

no off powder was observed.